Light projector



Nov. 24 W25- R. C. GOWDY LIGHT PROJECTOR Filed March 18, 1924 2 Sheets-Sheet 1 Nov. 24 1925 02 R. c. GOWDY LIGHT PROJECTOR Filed March 18, 1924 2 Sheets-Shaw; 2v

FTQQ

- Hamilton and State of Ohio,

i art of focusing such lamps.

Patented Nov. 24, 1925.

' UNITED S TES 1,5 2,502 PATENT OFFICE.

ROBERT CIJYDE GOWDY, or CINCINNATI, oIIIo, ASSIGNOR. BY MESNE ASSIGNMENTS. To THE AMERICAN FLA'ILITE COMPANY, or CINCIN ATI, OHIO, A CORPORATION.

- OF OHIO.

LIGHT PRoJECTon.

Application filed March 1 8,1924. SeriaLNo. 699,972.

' To all 'whu-naz't may concern:

Be 1t known that I, ROBERT CLYDE Gowoy,

a citizen of the United States of America,-

residing at Cincinnati, in the county of have invented certain new and useful Improvements in Light Projectors, of which the following is a specification, reference being had therein to the accompanying drawing. g

This invention has for an object to produce a light projecting reflector, the curva ture of which is so designed as to permit of considerable variation in the position of the source of light relatively to the focal center of the reflector, without effecting the resultant. shape and distribution of the resultant pattern produced by the beam of light projected from the reflector upon an intercept- .ing plane, an additional object being to produce a reflector, the curvature of which,

particularly adapts it to use in reflector constructions of configurated formations. .A further object is to produce a reflector ,of configurated type, which, because it is constructed upon curvature lines permitting of relatively great variation in the position of the sourceof light relatively to the focal center, readily adapts itself to the production of a device designed to permit of the quick change of an existing type of automobile head lamps into one of approved type having maximum light projecting qualities and which will comply with all legal lighting requirements.

A further object is to produce a device employing a reflector which embodies the novel construction curvature to which I have referred above, the purpose of the device being to adapt the usual automobile head lamp, without change or renewal of any of its parts, to use in localities requiring, lighting regulations and to permit of the installation and -use of the device by any one whether he be skilled or unskilled in the These and other objects are attained in the reflector construction and head lamp. adaptor device described in the following ,fl'specification and illustrated in the accompanying drawings in which:

Figs.- 1 to 4:- i'nclusive are diagrammatic '.views illustrative of the new reflector curvature which I have devised to render accurate focusing adjustments of the light source ,wholly unnecessary to bring a beam' of light projected thereby into full compliance with established legal requirements relating to such matters.

Fig. 5 is a sectional elevation'of an automobile head lamp ;equip ed with a reflector and adaptor device emliodying my invention.

lamp shown inFig.

thereof. .t F igs. 7 and 8 are respectively elevational 5 and taken on the line and sectional views of the connector I have j devised for mounting my improved adaptor in position relatively to the reflector of theexisting head lamp.

In the reflector curvature which I have endeavored to show diagrammatically in Figs. 1 to 4 inclusive, I have produced results which I have indicated by dotted lines, dash lines and solid lines. These lines I have shown in the several views, represent rays of light coming from a source of light located at three different positions. The point F shown in Fig; 1 represents the rearmost position which a source of light can occupy with relation to the true focal point F of the reflector, without causingdeparture of the shape and light distribution of the light beam from the legal light pattern required, and F, shown in Fig. 3, represents the-forwardmost position which the source of light may occupy with relation to the true focal point F of the reflector without causing departure of the shape and light distribution of the light beam from the legal light pattern required. In Fig. 1 I have shown by dotted lines a diagram of the light rays which-are produced when the light source the light source is located at F. Fig. 4 is 1 a composite view of the three Figs. 1, 2 and 3, so that comparison may be made as to the different directions taken by the sev-' eral rays when the light source occupies the true focal center F or either of the extreme 105 pisitions F or F".

7 In the design ofithe curve, which .I' have chosen to illustrate for demonstration by dividing it into concentric zones 9, 10, and

11, I have departed materially from the 0011- 110 Fig. 6 is a front sectional elevation of the ing as I have described it, does not exist, be-

ve'ntionalparabolic, hyperbolic, elliptic and other shapes usually employed in reflector formation. The central portion of'zone 9 is, for approximately its entire curved area, built'upon a curvature having a hyperbolic basis. but this curvature changes gradually so that it shades off into the curvature of zone which are involved in the production of the curve, would render the disclosure unnecessarily complicated. However, in describ ng the formation of the reflector curve in this.

manner I wish it to be understood that'it has been done to render the construction more readily understood. The actual zoncause I actually construct the reflector curvature so that it changes gradually from a hyperbolic curve at its central area,'until, by a gradual blending through a parabola, it runs into an elliptic curve toward the edge.

In the operation of the reflector, I have shown in Fig. 1 the direction taken by the light rays from the various portions of the reflector when the source of light is located at F. Reverting again to the convenient manner of describing my reflector by referring to different portions of it in terms of zones, I have shown rays 12 as representing any rays, as for example the outermost rays falling upon the portion 9. These rays or any which strike the portion 9, are reflected from its surface in directions somewhat as indicated by rays 12'. such rays taking a diverging forward direction with relationto each other and the axis of the reflector to produce a beam whose cross section is a ring of light with a dark center.

That portion of the reflector which is represented by zone 10, for purposes of this description, will receive rays such as 12 and 13, at any point upon the zone 10 from the source of light F, the reflected rays therefrom taking a direction diverging from the central beam produced by rays 12, but with the limiting rays 13 and 13 thereof passing from the reflector in a slightly diverging direction relatively to each other and to the reflector axis. a

The outer portion or zone 11 produces results which differ materially from those produced by the beams of light projected from zones 9 andlO which have been described. Taking the rays of light'13 and 14 which are projected from the source of light F, the general character or shape of the beam which results therefrom after they are reflected from the surface of zone 11 is represented by rays 14 and 14". Rays 14 which lie toward the axis of the reflector, converge slightly with relation to each other, while rays 14 whichlie toward the periphery of the reflector are parallel to the reflector axis, thus producing a. converging diverging beam.

F at which the source of lightcan be placed without affecting the total beam of light which the reflector will produce, the several smaller beams which form the component parts of the total beam operate as follows. The beam 1212 is of a diverging type and the beam 1313" is of a type having greater divergence. This would operate to leave a hole or conical dark region in the single beam thus produced. However, the outer beam which is produced by the rays 141-l is of such a nature that it approaches the central beam 12-12" and crosses the beam 13"13" so as to fill up the hole or conical dark region in the beams projected from zones 9 and 10. In the drawings space prohibits an extension of the lines indicating the beam outlines, but it may be seen quite readily thatv a continuation ofthe lines as shown. would eventually'produce the result described. The relative convergence, divergence and general 1ncl1nat1on of the reflected 1 Thus, by utilizing-the rearmost position rays as shown in the drawings, has purposely been materially exaggerated because the angles and displacements actually encountered in practice are too small to be shown in the drawings.

In Fig. 2 I have shown by full lines the incident and reflected rays when the source of light is located at the true focus F of the reflector. The reflected rays 22 resulting from the incident rays 22 are projected from the central portion or zone 9 of the reflector and form a central divergent beam of light as did the beam 1212 of the first descrip- 'tion, but thebeam is now solid. In the projection of the beam from zone 10, the reflected rays 2. "c3 produce a beam of rays parallel to the axis. duced by zone 11 consists of a convergent beam 24=24 which is again convergent divergent with respect to the axis, and throws an annular ring reinforcing the part of the beam surrounding the core projected by zone 10. This produces a compensation in the region previously illuminated by zone 10 when the light source was at F.

In Fig. 3 I have shown the general efi'ect produced by the location of the source of.

light at the forward positionlimit F of the light source. When in this position the. light reflected from the reflector zone 9 will result in a beam 32 -32' of less divergence than in 22'-22 but still solid throughout The light now prowith respect to the axis.

its axis, but this region has received additional illumination, as explained above, from zone 9. -The beam projected by zone 11 is again a convergent beam, convergent divergent with respect to the axis and of greater convergence than that previously obtained in rays 24'-24- when the source is located at F. The increased divergence of this beam after its rays cross, compensates the lllumination in the regions. previously illuminated by zone 9 when the source was at F.

In Fig. '4; I have shown, for purposes of comparison, the difference existing between the several beams I have described above.

This is accomplished by. superposing the severalvdiagrams shown in Figs. 1, 2 and 3, so

that the variation between them may bereadily seen. By carefullystudying each of the diagrams Figs. 1, 2and 3, in the light of that shown in Fig. 4, it will be-seen that at any point within the limits of' the indicated positions F, F the source of light may beplaced, and that the resultant beam will not be changed because the multitude of small beams which .enterinto the production of the large beam automatically compensate the illumination by their relative shifts. I

In Figs. 5 and 6 I have'shown an adaptation of my improved reflector ,curve to a form of lighting device in which a reflector of such curvature is particularly desirable. This device is designed to adapt the usual automobile headlamp to usage in connection with certain reflector constructions whlch are well known and, are designed to render the usual lamp legally usable 111 localities having lighting laws requiring certain light patterns and intenslties. The device which I have illustrated and am about to describe, I

' have chosen to term an adaptor for the reason that it adapts ordinary lamps to legal ,usage.

, tureI have described, but, for

is typical of a well-known type ofreflector' reflector 15 which is of the together with some 'means of fastemng the reflector in position. For the purpose of fastening the reflector I have provided a connector 16 of novel construction. The reflector 15 is constructed upon a basic curvature of the shape of the novel curvathe purpose of adapting theheadlamp to usage in compliance with the lighting regulations found in manyStates, I have shown the reflector as having the configurated formation 17 which now on'the market. The outerrilnor edge of the light source,-

connector may -f ar.=a's-.its,-adjustment screw 35 will diameter adapted to fit within the mouth of The connector 16 is provided with a body 20,.a spacing collar21 and a nut 22. The body 20 is arranged with a plug end 23 and a socket end 24,. The plug end is of the same diameter as that candescent bulb which is provided for fitting within the connector 25 of the lamp, and I the pins 26 and 27 which'are in, the plug, are placed similarly to those with which the usual bulb is provided for retaining it in position in the connector'of the lamp.

of the base of the usual in- Within the plug is an insulating block 28 which carries a. centrally located contact 29. This contactextends into the socket 24 of the body 20 so that its yielding contact end 30 will occupy a position in which the contact on the bulb base will engage the end 30 when the bulb 33 is placed in position. The socket end of the bodyis of the internal dimensions necessary to receive the base of the usual lamp bulb, and is provided with the usual bayonet slots 31 in which the oins of the lamp bulb seat in order that the b will be retained. These slots are identical ulb with the slots 32 with which the lamp connector is provided and operate to retain the lamp bulb in the same manner as though it iflange 36 on the collar bearing against the inner surface of the reflector surrounding the opening through which the connector is passed. The outer surface of the socket 24 1s screw threaded for a portion of its distance to receive fastening nut 22 so that the be secured to the adaptor reflector rigidly and in a non-adjustable POSF tion therewith, as shown in Figures 5 and 7. The adaptor-I havedisclosed, consists of a configurated orpartially configurated type so commonly 7 known,

Thus the connector is rendered a fixed eletioned that the bulb, when held-in the connector body, will have its filament lyingwholly within the limitations of themaximum and minimum positions of light source as indicated by F and F inFigs. 1 to 4 inclusive.

To secure the adaptor in position within the lamp reflector, the-bulb 33 of the adaptor may have been previously placed within the adaptor connector socket-if desired. The connector 25. of the lamp is advanced as carry it so that its slots 32,1are in an accessible position with relation to the pins 26 and which has previously been described, no adand seats the adaptor reflector therein bybringing its flanged'edge 18 tightly against the opening of the lamp reflector. Thus inadvertent dis lacement of the adaptor is prevented an because of the characteristics of the curve of the adaptor reflector,

justment is rendered necessary to bring the source of light into proper focal position to meet all the requirements of the laws de-.-

signed to regulate such matters. Particularly true is this when my improved adaptor is provided with a lamp bulb of the type commonly known in the trade as a precision bulb. By this is meant that the position of the filament in each bulb is within certain l mitations or tolerances as to position of the filament with relation to the locating pins on the'bulb base and as to the-size of the filament.

With the adaptorthus locked in position against displacement and vibration the closure 37 of the lamp is replaced to close the interior against dust and moisture. If the lamp, as previously used, has been equipped with a lens, it 'isabsolutely essential that plain glass 38 be substituted therefor when the configurated adaptor reflector is to be used. This is because the presence of a lens would destroy the advantageous results to be obtained by the substitution of the configurated reflector.

The reason for the design of a reflector curvature which will permit of a relatively great variation of position of light source is that no accurate focusing adjustment of the lamp bulb will be required in order to small details has rendered it ditficult forunskilled persons to adjust their own lamps so that they would comply fully with all the laws designed to regulate vehicle headlamp illumination.

Another reason .for-the design of a rei flector which will permit of a wide latitude inthe positionof the lamp bulb filament is that in designing a device such as I have described, no provision for separate focusing of the lamp bulb can be made conven- ,iently because the focusing device of the lamp proper is rendered useless for focusmg purposes by having to perform the functioning of retaining the adaptor in position. It would be quite inconvenient to have to provide for an additional focusing device for the adaptor, especially when the matter can be quite easily taken care of in the novel construction I have employed in the adaptor reflector.

Having thus described my invention what I claim is:

1. A reflector having a surface of revolution upon the axis of a curve which is hyperbolic centrallythereot between its ends, elliptic at and adjacent to its ends, and parabolic between the hyperbolic and elliptic portionsthereof, the hyperbolic, parabolic and elliptic portions of the curve blending gradually from one to the other.

2. A concave reflector having a basic curvature which varies radially to provide a series of concentric zones merging and developing one" into another, the basic curvature of one zone being elliptical, and a second zone hyperbolic.

In' testimony whereof I have hereunto afiixed my signature.

ROBERT CLYDE GOWDY. 

